Sadowsky Onboard Preamp v. Pedal Question

One of my favorite part of the Sadowsky basses I got to try was the passive tone knob that helped "round out" the sound of the preamp.

Is this something you can achieve by plugging a normal passive bass into a pedal like the Sadowsky preamp pedal? Is their a difference in how the signal runs from the pickup to the amp that means the sound wouldn't be the same as it would be with the onboard and passive rolloff setup?